Recently there has been employed a disk playback device of the type which includes a magazine containing several compact disks arranged in a stacked manner, a tray for supporting and transporting the disks from the magazine to a playback section of the device so that data, recorded on the disk, can be played back.
As shown in FIGS. 1 and 2, this type of disk playback device 170 is provided with a magazine housing 171 and a data playback section 172 adjacent to the magazine housing 171. The magazine housing 171 houses a magazine M containing a plurality of compact disks arranged in a stacked manner. The data playback section 172 plays back data from a compact disk "d" which is set in a tray "t" and which is fed out of the magazine M. A tray turning member 173 is located on the left side (as viewed in FIG. 1) of the boundary between the magazine housing 171 and the data playback section 172. The tray turning member 173 turns the tray "t" stored in the magazine M to transport the compact disk "d" to the data playback section, and also serves to return the tray "t" back to the magazine M. The tray turning member 173 consists of two arms extending in directions which are orthogonal to each other. Those arms are located at a corner of the magazine M, and face the two sides of the magazine which are orthogonal to each other. The tray turning member 173 is turned by means of a known tray turning mechanism 174 which is installed on the left side (as viewed in FIG. 1) of the data playback section 172.
The tray turning member 173 may be turned within a range of 90 degrees. The arm 173a of the member 173 faces the side wall "to" of the tray projected from a narrow opening as shown in FIG. 2. To feed a tray "t" holding a desired compact disk "d" and to set it at a predetermined position (clamping position) in the data playback section 172, the magazine M is vertically moved by a mechanism (not shown), to face the side wall "to" of the tray "t", and the tray turning member 173 is turned counterclockwise, to turn the tray "t" about a pin 180 provided at a corner of the magazine M, by 90 degrees. To return the tray "t" back to the magazine M, the tray turning member 173 is turned clockwise.
A disk receiving depression 181 is formed in the center portion of the tray "t". The depression 181 has a diameter which is large enough to accept a compact disk having a 12 cm diameter. However, recently, a small compact disk (8 cm in diameter) has been used. As shown in FIG. 3, to set this small compact disk in the depression, a spacer ring S is set in the depression 181 and the small compact disk "d1" is placed within the spacer S.
After the tray "t" is set at the predetermined location in the data playback section 172, the disk "d" (FIG. 2) or "d1" (FIG. 3), is clamped by a support wheel 191 of a spindle motor 190 disposed above the disk and a clamper 192 disposed below the disk. The disk "d" or "d1" is turned by a spindle motor 190. Data is played back from the compact disk by means of a pick-up (not shown). To clamp the disk, the clamper 192 is lifted through an opening O of the tray "t" and cooperates with the support wheel 191 to clamp the disk on the tray "t".
As indicated above, the magazine M is set in the magazine housing 171 of the disk playback device 170. A check is made as to whether or not a disk is present in each tray within the magazine M. To detect the presence of a disk in the tray, an optical detecting member 94 is installed near the clamper 192. The detecting member 94 checks as to whether or not the disks are present in the trays, through the opening O of the tray. More specifically, to make the check, the trays are successively pulled out of the magazine and set in the clamped position, and then the presence of the disk in each tray is checked by the detecting member 94. Accordingly, according to this check operation, a relatively long time is necessary to check the presence of the disks since each disk must be fully pulled out of the magazine and set in the clamp position.
As shown in FIG. 4, the clamper 192 is supported at the distal end of a clamp arm 193. A support shaft 194 is mounted on the distal end of the clamp arm 193. The support shaft 194 is inserted into the center portion of the clamper 192. A support plate 195 is mounted on the top end of the support shaft 194. A recess is formed in the center portion of the upper surface of the support plate 195. The recess receives a ball 196, which is mounted to the top of a projection 197 formed above the center portion of the clamper 192. The reverse side of the support plate 195 faces a surface 198. When the clamp arm 193 swings, the clamper 192 moves in a vertical direction. A rounded rise 201, located at the center portion of the clamper 192, is inserted into an opening placed in the center portion of the compact disk "d". When the rounded rise 201 engages with the support wheel 191, the compact disk "d" is rotatably held.
As shown in FIG. 4, the clamper 192 is tiltably supported at the distal end of the clamp arm 193. With this arrangement, when the clamp arm 193 swings, the attitude of the clamper 192 changes. Accordingly, the center of the clamper 192 does not necessarily coincide with the center of the opening 200 of the disk "d". More particularly, when the disk playback device is set in an erect position, the clamper 192 will go down and fails to hold the compact disk at the center portion. As indicated above, to clamp a disk, the clamper 192 is lifted through an opening of the tray "t" and cooperates with the support wheel 191 to clamp the disk on the tray "t". Referring to FIG. 5, when the clamper 192 is lifted and the disk is clamped between the clamper 192 and the support wheel 191, to gain a sure clamping, a-horse-shoe disk guide 150 holds down and guides the upper surface of the disk. Three pins 151, 151 and 151 are planted on the disk guide 150, and are appropriately spaced from one another. The disk guide 150 is guided by the pins 151 to move in a vertical direction when a disk guide mechanism (not shown) is driven.
The disk guide 150 is installed at such a location as to hold the circumference of a compact disk having a large diameter of 12 cm. In this regard, it is rare that data is recorded in the portion of the disk near its circumference. Therefore, it is desirable that the disk guide 150 be installed at such a location on the disk. To guide the large disk, the disk guide 150 may be installed around the disk. However, with this installation, the disk guide 150 fails to guide a small compact disk "d1" of 8 cm in diameter. To hold the small compact disk "d1" on the tray "t", the adaptor ring S is put inside and along the circumference of the depression 181, and the small disk "d1" is placed in the space defined by the adaptor ring S.
The approach to hold the disk using the adaptor ring S, however, involves the following problem. The adaptor S, which is imprecisely finished, is often not correctly set in the depression 181. If the disk guide 150 holds down the incorrectly set adaptor, however, the small compact disk "d1" is displaced from the predetermined position.
Referring to FIG. 6, to avoid a horse-shoe disk guide 150 from obstructing the turning motion of the tray when the tray "t" is fed to the clamp position, the disk guide 150 is positioned above the upper surface of the tray "t" with a clearance C therebetween. To clamp the disk "d" placed in the tray "t", a clamper 192 is moved upward and causes the disk "d" to make contact with the disk guide 150. Under this condition, the clamper 192 is further moved upward, so that the disk "d" is nipped between the support wheel 191 and the clamper 192. To put the disk "d" back to the tray "t" after the data is played back from the disk, the clamper 192 is moved down to disengage the disk "d" from the clamper 192. At this time, the disk guide 150 descends up to a level as shown in FIG. 6. When the disk "d" is lowered, it should be correctly put back to the disk receiving depression 181 of the tray "t". However, the conventional disk playback device is not provided with a mechanism to correctly put the disk back to the depression. Therefore, in such a case, the disk "d" may be incorrectly placed in the disk receiving depression. Particularly where the disk playback device is used in an erected state, when the disk is made to disengage from the clamper 192, the related mechanism frequently fails to return the disk to the depression 181 of the tray "t". The frequency of the disk return failure when the playback device is used in an erected state is higher than that when it is horizontally placed in use. When the disk return failure occurs, the disk "d" incorrectly placed in the tray "t" is put back to the magazine, leading to jamming of the disk "d".
FIG. 7 shows a playback device 170 which includes means for detecting when a magazine is inserted in the device and when the magazine is locked in the device. More particularly, after the magazine M is completely inserted into the magazine housing 171, the tray "t" is pulled out of the magazine and transported to the data playback section 172. In this case, a magazine detect arm 104 detects that insertion of the magazine M is completed. A lock detect arm 103 detects the completion of locking the magazine M by a lock arm 107. After the insertion of the magazine is completed, the magazine M is locked so as not to be ejected from the magazine housing 171. The magazine detect arm 104 is swingable on an axis 111, and is biased counterclockwise as viewed in the drawing, by means of a spring 106. When the leading edge of the inserted magazine M comes in contact with the distal end of the magazine detect arm 104, the detect arm 104 is turned clockwise as viewed in the drawing, to operate a detect switch 110. When the lock arm 107 is put into a recess on the side wall of the magazine M, the distal end of the lock detect arm 103, which, together with the lock arm 107, is turned on an axis 108 to lock the magazine M, presses another detect switch 109, thereby to detect the completion of the locking the magazine by the lock arm 107. In this way, the completion of the insertion of the magazine M, and the completion of locking of the magazine M are detected in successive order. Following the successive detections, a desired tray "t" is transported to the data playback section, and a playback operation is carried out.
In the known disk playback device, two detect mechanisms are employed; one for detecting the completion of the magazine insertion, and the other for detecting the completion of locking the magazine. That is, the detect switches 109 and 110 are connected in series. The data playback operation will never start until both the switches are operated. It is clear that use of the two detect switches makes the detect mechanism complicated in construction, and that the complicated mechanism leads to an increase in manufacturing cost.